Blockchain technology, also referred to as a distributed ledger technology, is an emerging technology in which several computing devices jointly participate in “accounting” to maintain a complete distributed database. The blockchain technology features decentralization and transparency, each computing device can record data in the database, and the data can be synchronized rapidly between the computing devices. Therefore, using the blockchain technology to establish a decentralized system and record various execution programs in a distributed database of a blockchain for automatic execution has been widely applied to many fields.